Improved location technology of perforators of anterolateral thigh flap for Chinese patients

The anterolateral thigh (ALT) flap has been widely used in reconstruction of soft tissue defects. The anatomic variations of perforators increase the difficulties of flap elevation. The ABC system has been described for locating the most common three perforators in Western populations. Less evidence has been found regarding whether it is suitable for Chinese population. The purpose of this study is to explore the improvement of preoperative location technology and flap design for Chinese people.

Detection for perforator signals on the bilateral thigh surface was perfromed on 50 Chinese adults using handheld Doppler. Define the A-P line as the line between the anterior superior iliac spin (ASIS) and the superolateral corner of the patella (P). We defined a coordinate system on the thigh surface to record the data of each signal point. The A-P line was y-axis in this coordinate system, and the midpoint of the line was the zero point. The data of these signals were recorded in the form of coordinates. Statistics and mathematic methods were used to analyze the regularity of signal distribution and the correlation between body mass index (BMI) and signal distribution. The findings were applied in five patients who underwent the ALT flap transplantation to confirm its clinical value.

The results showed that most of the signals appeared near the A-P line. Most signals were located 1 cm lateral (mean 0.5 cm lateral) to the A-P line. The mean vertical distance between perforator B and perforators A and C was 4 cm. More perforator signals were detected at the two horizontal level (as shown in the picture above) than other horizontal levels. The rate of accurate preoperative detection was 40% (6 of 15 perforators) and the error rate was 20% (3 of 15 perforators). The mean deviation was 1.34 cm, which is acceptable for clinical application. The mean vertical distance between perforator B and perforators A and C in clinical study (4.81 cm) corresponded to the finding of the Doppler study (4.2 cm), whereas the mean distance between perforators and the A-P line (1.57 cm) was more than the Doppler finding (0.48 cm).

The A-P line is still a reliable guiding line for Doppler detection and flap design. The ABC system is suitable for the Chinese population but must be adjusted: perforator B is marked first at the midpoint and 0.5 cm lateral to the A-P line and perforators A and C are marked 4 cm distal and proximal to perforator B, respectively. In designing the flap, the region 3 cm around point B and the region between the two horizontal planes at point B and 4 cm lower should both be contained into the flap, no matter what the finding of Doppler detection is.